Methods and apparatus for infrared reflecting system

ABSTRACT

An infrared reflecting system according to various aspects of the present invention includes an infrared reflective material and at least one layer. The infrared reflecting material is configured to deflect infrared radiation. The layers inhibit heat transfer via convection and/or conduction and/or obscure the infrared reflective material.

BACKGROUND OF THE INVENTION

Three primary mechanisms facilitate heat transfer: convection,conduction, and radiation. Convection is the transfer of heat by fluidcurrents. As a fluid rises in temperature, it often expands and movesaway from the heat source, taking energy with it. The warm air is thenreplaced with colder air. The human body continuously warms a thin layerof air next to the skin. If this layer is drawn away through convection,then the body feels cold. To combat heat loss through convection, humanswear clothes. Clothing attempts to minimize the amount of warm air thatis lost by trapping the warm air close to the body.

Conduction is the transfer of heat through molecular movement within amaterial, without any motion of the material as a whole. Heat transferbetween two materials occurs when the materials are in direct physicalcontact and have different temperatures. The rate of heat transferred isdependent upon the surface area of contact and the conductivity of thematerials. Materials that pass heat easily are known as conductors,while materials that do not pass heat easily are known as insulators.Many metals have a particularly high rate of heat transfer and are thusgood conductors. Plastic, wood, and cotton do not transfer heat easily,and thus are good insulators. To reduce the heat loss throughconduction, clothing generally is made of materials that are goodinsulators.

Radiation is the transfer of heat through electromagnetic energy. Thisform of energy transfer does not require the presence of matter tooccur. Heat transfer through radiation is from warmer to cooler objects,and occurs in all directions.

Heat transfer may also occur through a mixture of these primarymechanisms. For example, the human body may lose heat throughconvection, conduction, and radiation by having skin exposed to air andin contact with a conductive material. This makes the prevention of heatloss a more complicated problem.

SUMMARY OF THE INVENTION

An infrared reflecting system according to various aspects of thepresent invention includes an infrared reflective material and at leastone layer. The infrared reflecting material is configured to reflectinfrared radiation. The layers inhibit heat transfer via convectionand/or conduction and/or obscure the infrared reflective material.

BRIEF DESCRIPTION OF THE DRAWING

A more complete understanding of the present invention may be derived byreferring to the detailed description and claims when considered inconnection with the following illustrative figures. In the followingfigures, like reference numbers refer to similar elements and stepsthroughout the figures.

FIG. 1 is a cross-sectional view an infrared reflective material betweentwo layers.

FIG. 2 is a view of an infrared reflective material including wovenstrands.

FIG. 3 is a cross-sectional view of an infrared reflecting systemincluding a covering.

FIG. 4 is a view of an infrared reflecting system having a flexibleinfrared reflecting material and layers.

Elements and steps in the figures are illustrated for simplicity andclarity and have not necessarily been rendered according to anyparticular sequence. For example, steps that may be performedconcurrently or in different order are illustrated in the figures tohelp to improve understanding of embodiments of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present invention is described partly in terms of functionalcomponents and various processing steps. Such functional components maybe realized by any number of components configured to perform thespecified functions and achieve the various results. For example, thepresent invention may employ various elements, infrared reflectingmaterials, conduction inhibitors, convection inhibitors, coveringmaterials, and the like, which may carry out a variety of functions. Inaddition, the present invention may be practiced in conjunction with anynumber of applications and environments, and the systems described aremerely exemplary applications for the invention. Further, the presentinvention may employ any number of conventional techniques formanufacturing, assembling, and the like.

Referring now to FIG. 1, an infrared reflecting system 100 according tovarious aspects of the present invention may be implemented inconjunction with an infrared reflecting material 110 between two layers112, 114. The layers 112, 114 may be configured to face an internalenvironment 116 and/or an external environment 118. Generally, theinfrared reflecting system 100 inhibits transfer of infrared radiationfrom one environment to the other. The layers 112, 114 inhibit heattransfer between the environments via conduction and convection, and theinfrared reflecting material 110 inhibits heat transfer via radiation.For example, the internal environment 116 may be a human body, ananimal, an object or an open space, and the external environment 118 maybe a cold or warm climate, a sensor, or liquid. In various embodiments,the infrared reflecting system 100 may include only one layer 112disposed on one side of the infrared reflecting material 110, two layers112, 114 with the infrared reflecting material 110 disposed between thelayers 112, 114, or multiple layers 112, 114, disposed one or both sidesof the infrared reflecting material 110.

In the present embodiment, the infrared reflecting system 100 includesat least one layer 112, 114 on each side of the infrared reflectingmaterial 110. The layers 112, 114 on each side of the infraredreflecting material 110 impede heat conduction and convection from thesurface of the infrared reflecting material 110. The infrared reflectingsystem 100 may also be rigid, resilient, or flexible, such that theinfrared reflecting system 100 may maintain a substantially constantshape or operate like a fabric to conform to a surface.

The infrared reflecting material 110 may comprise any suitable materialthat is at least partially reflective of infrared radiation (i.e.,wavelengths of about 0.70 micrometers to about 1000 micrometers). In oneembodiment, the infrared reflecting material 110 exhibits a highinfrared reflectivity, for example approximately 0.35 or more forselected bands of infrared radiation or an average reflectivity ofapproximately 0.35 over the infrared band, under the conditions forwhich the infrared reflecting system 100 is adapted. In alternativeembodiments, the infrared reflecting material 110 exhibits a higherreflectivity, for example approximately 0.50, 0.7, 0.8, or 0.9 or morefor selected bands of infrared radiation, or an average reflectivity ofapproximately 0.50, 0.7, 0.8, or 0.9 over the infrared band. Generally,higher reflectivity in the infrared band improves the performance of theinfrared reflecting system 100. In the present embodiment, the infraredreflecting material 110 comprises a material that reflects infraredradiation and exhibits low absorptivity of infrared radiation. Forexample, infrared reflecting material 110 may comprise one or more ofseveral metals, such as copper, aluminum, gold, silver, beryllium,chromium, molybdenum, nickel, platinum, rhodium, tungsten, relatedalloys, and the like, that exhibit relatively high reflectivity ofinfrared radiation. Alternatively, the infrared reflecting material 110may comprise a material having a high dielectric constant in thefrequency range of interest, such as plastics, nylons, and/or rayons,treated with a high infrared reflectivity material and/or a highconductivity material. The infrared reflecting material 110 may beimpregnated or otherwise treated with additional materials to create theinfrared reflecting material 110 having any appropriate characteristics.

The infrared reflective material 110 may be configured in any suitablemanner. In various embodiments, the infrared reflective material 110 maycomprise a rigid and/or a flexible material. For example, the infraredreflecting material 110 may include a foil, film, strands, or othermaterial including an infrared reflecting material, or foil, film,strands, or other material with a coating of infrared reflectingmaterial. The infrared reflecting material 110 may be configured in anysuitable manner, such as having any suitable thickness, material,reflectivity, flexibility, strength, and the like. The infraredreflecting material is suitably thick enough to effectively reflectinfrared radiation.

For example, referring to FIG. 2, one embodiment of the infraredreflecting material 110 may comprise multiple woven strands 200. Thestrands 200 may comprise any appropriate material, such as threads orwire, and may be solid, hollow, parsed, twisted, or otherwiseconfigured. In the present embodiment, the strands 200 are woventogether in any suitable pattern to form a flexible fabric, allowing thefabric to conform to a surface or shape. Where the strands 200 have acoating, the coating may be applied before or after weaving. In oneembodiment, the infrared reflecting material 110 includes a conductivefabric from Sauquot Industries comprising fiber strands coated withsilver, gold, or other infrared reflective material, and woven to form afabric. The strands may be configured, however, in any suitable manner,such as any suitable thickness, weave density, type of weave, material,reflectivity, flexibility, strength, coating thickness, coatingmaterial, coating reflectivity, and the like.

The infrared reflecting material 110 may also be adapted according tothe particular application. For example, the infrared reflectingmaterial 110 may be durable and resistant to corrosion, and may compriseany suitable dimensions and thickness. Further, the infrared reflectingmaterial 110 may be configured and/or shaped for any suitable purpose,such as retaining heat, shielding from heat, shielding from sensors, orcommunication. For example, the infrared reflecting material 110 maycomprise a large sheet, tarp, or other cover that may be interposedbetween an infrared sensor and an item to be hidden, such as a person orequipment. In another embodiment, the infrared reflecting material 110may form letters or other symbols. The letters, symbols, or the like maybe visible via an infrared sensor, but would be obscured by the layers112, 114 that may transmit infrared radiation but opaque to visiblelight. The letters and/or symbols may be used for any suitable purpose,such as to identify a wearer or designate a particular area or item ofinterest. In another embodiment, the infrared reflecting material 110may be configured for alternative functions, such as to form an antenna.

The layers 112,114 may inhibit heat transfer via convection and/orconduction, and may conceal and/or protect the infrared reflectingmaterial 110. The layers 112, 114 may be comprise any suitable material,and may be configured in any suitable manner, such as rigid structuresor flexible sheets having any appropriate dimensions or thicknesses. Inone embodiment, at least one of the layers 112, 114 may comprise avacuum. In another embodiment, referring to FIG. 3, the layers 112, 114may comprise insulation 316 and covering materials 312, 314. Theinsulation 316 inhibits heat transfer via conduction and/or convection.The insulation 316 may comprise any suitable material for inhibitingconvection and/or conduction, such as a conventional thermal insulator,for example, wool, silk, cotton, leather, natural fibers, syntheticfibers, and other appropriate materials.

The covering materials 312, 314 lay over the insulation 316. Thecovering materials 312, 314 may serve any suitable purpose, such as toprotect the insulation 316 and/or infrared reflecting material 110, addcomfort, provide an interface for mounting or connecting to anothersystem, or other suitable purpose. For example, in one embodiment, oneor both of the covering materials 312, 314 comprises a waterproofcovering for repelling moisture. The covering materials 312, 314 mayalso substantially block or transmit visible light. Separate coveringmaterials 312, 314 and insulation 316 may be beneficial where theinsulation 316 is poorly suited for exposure. For example, in ahousehold insulation system, the insulation 316 may comprise fiberglass,and the covering material 312 drywall. Another example is a downcomforter, where the insulation 316 comprises down feathers and thecovering 312 is a cotton, nylon or silk material.

The infrared reflecting system 100 may be configured and/or adapted forany suitable application or environment. For example, the layers 112,114 and the infrared reflecting material 110 may be permeable to watervapor but impermeable to liquid water, such as by forming smallperforations in the layers 112, 114 and the infrared reflecting material110. Thus, the infrared reflecting system 100 provides a “breathable”system that allows humidity to escape, but repels the elements, likerain and snow, while inhibiting the heat loss. In other applications,such as for a dry suit or a tarp, the infrared reflecting system 100 mayinclude substantially waterproof materials or be treated with awaterproofing agent. Alternatively, the infrared reflecting system 100may be permeable to water but configured to retain heat, for exampleusing larger holes in the layers 112, 114 and the infrared reflectingmaterial 110, for use in various applications such as a wetsuit.

FIG. 4 illustrates an infrared reflecting system where the infraredreflecting material 110 and the layers 112, 114 are flexible, forexample to conform to a surface. The infrared reflecting system 100 maybe configured to conform to any kind of garment, blanket, survivalenclosure, tarp, or other cover or protection. For example, the infraredreflecting system 100 may be incorporated into cold weather garments,footwear, and headgear, as well as environmental protective gear, suchas sleeping bags, tents and shelters, ground pads, and survivalenclosures. The flexible infrared reflecting system 100 may also beincorporated into diving suits, including wet suits and dry suits,blankets, bedding, tarps, medical coverings, awnings, and umbrellas. Forinfrared shielding or reflection, the flexible infrared reflectingsystem 100 may also be incorporated into military items as well, such ascamouflage clothing, equipment, and material, military decoy material,and infrared ground marking targets. In alternative embodiment, theinfrared reflecting system 100 is rigid, for example for householdinsulation, packaging materials, storage containers, pool covers, and/orwindow blinds. Furthermore, the system may be used to shield a person,object, or area from sensors, such as for a privacy garment thatinhibits millimeter wave radar or infrared sensors from scanningindividuals wearing the garment.

The particular implementations shown and described are illustrative ofthe invention and its best mode and are not intended to otherwise limitthe scope of the present invention in any way. Indeed, for the sake ofbrevity, conventional materials, configurations, coatings, and otherfunctional aspects of the systems may not be described in detail.Furthermore, the connecting lines shown in the various figures areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. Many alternative or additionalfunctional relationships or physical connections may be present in apractical system.

The present invention has been described above with reference to apreferred embodiment. However, changes and modifications may be made tothe preferred embodiment without departing from the scope of the presentinvention. These and other changes or modifications are intended to beincluded within the scope of the present invention, as expressed in thefollowing claims.

1. An infrared reflecting system comprising: an infrared reflectingmaterial with high infrared reflectivity; and an inner layer and anouter layer, wherein: the layers inhibit convection and thermalconduction; and the infrared reflecting material is disposed between thelayers.
 2. An infrared reflecting system according to claim 1, whereinthe infrared reflecting material comprises a plurality of strands.
 3. Aninfrared reflecting system according to claim 2, wherein the infraredreflecting material comprises a woven material.
 4. An infraredreflecting system according to claim 2, wherein the strands comprise atleast one of a metal, a metal coating, and a material having a highdielectric constant.
 5. An infrared reflecting system according to claim1, wherein at least one layer further comprises an insulation and acovering.
 6. An infrared reflecting system according to claim 1, whereinthe infrared reflecting material further comprises a corrosion resistantmaterial.
 7. An infrared reflecting system according to claim 1, whereinthe infrared reflecting material and the layers are flexible.
 8. Aninfrared reflecting system according to claim 1, wherein the layers andinfrared reflecting material are permeable to at least one of water andwater vapor.
 9. An infrared reflecting system according to claim 1,wherein the infrared reflecting material contains at least one ofsymbols and letters.
 10. A method for reflecting infrared rayscomprising: providing an infrared reflecting material; and placing theinfrared reflecting material between a first layer of convectioninhibiting and thermal conduction inhibiting material and a second layerof convection inhibiting and thermal conduction inhibiting material. 11.A method for reflecting infrared rays according to claim 10, wherein thematerial substantially conforms to a surface.
 12. A method forreflecting infrared rays according to claim 10, wherein the systemcomprises at least a portion of at least one of a survival blanket and asurvival enclosure.
 13. An infrared reflecting system according to claim10, wherein the layers and infrared reflecting material are permeable toat least one of water and water vapor.
 14. An infrared reflecting systemcomprising: a flexible infrared reflecting fabric exhibiting highinfrared reflectivity; and an inner layer and an outer layer, whereinthe layers inhibit convection and thermal conduction; and the infraredreflecting material is between the layers.